i rebuilt the transmission on 2000 ford f150 now it won't move when i put it in

Check proper fluid level. When u put the valve body together did you align the manual valve to the internal rooster comb linkage?

if you rebuilt it yourself,i am sure you put the correct tranny fluid back in it.if it is the 4r70w it calls for the mercon 5 in my truck.i had it rebuilt 5 years ago and the guy that owns the tranny shop said he will not rebuild any transmission without adding a bottle of duralube (red bottle)from napa, in with the required fluid.he uses the red on every tranny rebuild no matter what type vehicle.